Rotor and drive shaft with frangible coupling



Nov. s, 1949 G. J. KNUSQNl 2,487,449

RGTOR AND DRIVE SHAFT WITH FRANGIBLE COUPLING Filed Dec. 21, 1944 A T TOR/VE Y Patented Nov. 8, 1949 ROTOR AND DRIVE SHAFT WITH FRAN GIBLE COUPLING Giltner J. Knudson, Guilford, N. Y., assignor to Bendix Aviation Corporation, New York, N. Y., a corporation of Delaware Application December 21, 1944, Serial No. 569,187

5 Claims.

l This invention relates to machine parts and more particularly to structures such as rotary type pumps having rotors comprising a plurality of assembled parts or the like.

One of the objects of the present invention is to provide a novel combination of rotatable elements in a structure whereby continued rotation of one of said elements is assured in the event others of said elements are prevented from rotating, such as by seizure during operation.

Another object of the invention is to provide a structure of the above character whereby the assembled parts of a combination of rotatable elements may be disassembled after extended use without difliculty and without the application of destructive forces.

Still another object is to provide a novel rotary pump which may be readily and inexpensively constructed and assembled and which may be readily and quickly disassembled for inspection, cleaning and repair.

A further object is to provide apparatus of the above character embodying novel means for 1ubricating relative rotating parts thereof.

Still another object is to provide a novel structure wherein a rotary type pump is combined in a novel manner with a housing therefor and a drive shaft rotatably mounted in said housing.

The above and further objects and novel features of the invention will more fully appear from the following detailed description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only and are not intended as a definition of the limits of the invention, reference for this latter purpose being had primarily to the appended claims.

In the drawings, wherein like reference characters refer to like parts throughout the several views,

Fig. 1 is a longitudinal vertical section through a rotary type pump embodying one form of the invention, the section being taken substantially on line I-I of Fig. 2; and

Fig. 2 is a transverse section of said pump taken substantially on line 2-2 of Fig. 1.

The single embodiment of the invention illustrated in the drawings, by way of example, is shown in the form of a rotary, vane type of air pump which is adapted for use in supercharging the housing of an ignition device or the radio shielding harness of an ignition distribution system, for example. In the form shown, the pump per se is mounted in and enclosed by a three-part housing comprising a base or end member 5, an intermediate member 6, and a. cover or end member 1. Base member 5 may be provided with radially extending -ears or lugs (not'shown) for use in securing the housing to the casing of an engine or the like. The two end members 5 and 1 of the housing are cup-shaped and cooperate with central member 6 to form an enclosed substantially cylindrical space for housing the pump means and lubricating means therefor to be hereinafter fully described.

End member 5 of the housing has a plurality of st'ud bolts 8 mounted therein and projecting axially therefrom. Bolts 8 are preferably threaded into member 5 and secured in place by means of pins 9. Housing members 6 and 1 have aligned openings for receiving bolts 8 and the three housing members are secured together by means of said bolts and nuts I0 which are threaded onto the outer ends of said bolts. The proper angular positioning of the three housing members is obtained by suitable dowels II, Il (Fig. 1).

The casing of the rotary pump which is enclosed and held in assembled relation by the above described housing comprises a cylindrical member I2 and circular end plates I3 and I4. The

latter are fitted into cylindrical portions or bores in housing members 5 and 1, respectively, and are angularly positioned therein by dowels I5, I5 which engage slots in the peripheries of said end plates. The inner faces of end plates I3 and I4 engage opposite ends of cylindrical casing member I2 and the outer faces thereof engage shoulders in housing members 5 and 1, respectively. The dimensions of the parts are such that the pressure applied by nuts I0 is eiective to firmly clamp the end plates I3, I4 and casing member I2 together, there being a slight clearance between the ends of housing member 6 and end members 5 and 1 when the apparatus is assembled. Casing member I2 preferably has a. tight shrink flt in housing member 6 or the same may be secured therein by any suitable means.

For purposes to more fully appear hereafter, each of the end plates I3 and Il has a circular opening therein which is eccentric with`respect to the periphery thereof. Tightly tted into each of said openings is a sleeve I6 of porous bronze or other equivalent material. The inner ends of sleeves I6 are externally flanged and the flanges t into grooves in end plates I3 and I4 to prevent outward movement of the sleeves relative to the plates and the plane faces of the inner ends of said sleeves project a slight distance inwardly beyond the inner faces of end plates I3 and I4, this distance being too slight to illustrate in the drawings. The outer ends of sleeves I6 project a substantial distance beyond the outer faces of plates I3 and I4 and support a plurality of oil soaked rings I1 of felt or similar material. A corner of a shoulder on each of sleeves I6 may be swedged or spun over against the outer faces of plates I3 and I4, as shown, to further secure the sleeves in place.

A rotatable shaft I8 extends freely through sleeves I6, IS and has a rotor mounted thereon for rotation therewith in the pump casing I2`, I3, I4. The rotor comprises a main cylindrical member I9 which is concentric with shaft I8 and is keyed thereto by a key 20. Since shaft I8 is eccentrically mounted in casing member I2 but is concentric with rotor member I9, a crescent shaped space 2l (Fig. 2) is formed within the pump casing, the parts being assembled so that rotor member I9 has a close running clearance with the wall of cylinder I2 at one side of the shaft. The periphery of rotor member I9 has a plurality of radial slots 22 which extend throughout the axial length thereof for slidably receiving centrifugally actuated vanes 23. Rotor member I9 is preferably cast out of metal and vanes 23 may be made of any suitable material, such as a plastic or phenolic material. During rotation of rotor I8, I9 the vanes 23 are thrown outwardly into fluid-tight engagement with the inner wall of cylindrical casing member I2 by centrifugal force. If desired, said vanes may also he pressed outwardly by light springs (not shown) Circumferentially speaking, one end of crescent shaped space 2l is connected to atmosphere or some other source of a suitable gaseous medium through registering openings 24, 25 in cylindrical members v6 and I2, respectively. A fitting 26 with a filter 27 therein may be provided for cleaning and/or drying the air which enters the pump. As the rotor rotates in a clockwise direction, as viewed in Fig. 2, air is drawn in through port 25, compressed between successive vanes 23 in a manner well understood in the art and released through an outlet 28 formed by ports in members 6 and I2.

Shaft I8 is rotatably supported adjacent opposite ends thereof in ball or similar bearings 29 and 30, each of which is preferably of the grease packed type, the grease being retained and the passage of air being substantially prevented by shields 3l extending between the inner and outer races of the bearings. Bearing 29 is removably held in housing member by a retaining plate 32 and screws 33. Shaft I8 extends through the inner race of bearing 29 and said race is positioned on the shaft by a shoulder on the latter and a nut 34 threaded onto the shaft. Bearing 30 has the inner race thereof removably secured against a shoulder on shaft I8 by a retaining nut 35 and is slidably received by a cylindrical portion of cover I of the housing.

End cover 1 is provided with a plugged oil hole 36 through which the oil supply in felt rings I'I may be replenished. A similar hole (not shown) may be provided in end member 5. Oil from wicks I1 is conducted through porous metal sleeves I6, IIS to the inner walls of the pump and serves to lubricate the adjacent surfaces of the pump casing I2, I3, I4 and rotor I9, 23. In order to prevent excessive wear, rotor member I9 has endwise thrust rings 31, 37 set in the ends thereof for engagement with the inner ends of sleeves I6, I 6. The outer surfaces of rings 31, 31

4 are preferably flush with the ends of rotor member I9 so that the clearance space between the ends of the rotor and the end plates I3, I4 of the pump casing is determined by the inward projection of sleeves IB, as described above.

For the purpose of preventing the accumulation of rust between shaft I8 and rotor member I9 and for preventing stoppage of the shaft in the event the rotor should seize in the pump casing, the shaft and key 20 are novelly constructed and assembled. The shaft is hollow and is plugged at the open end by a cork 38 or the like to provide a lubricating oil chamber 39 which is filled with oil during the initial assembly of the parts. Key 2U is made of phenolic or like material which will carry the normal load but will shear off at the periphery of the shaft, if the rotor seizes or is otherwise overloaded, to permit continued rotation of the shaft without further damage to the parts. In order that the relatively moving engaging surfaces of shaft I8 and rotor member I9 may be adequately lubricated in the event key 20 is sheared, the key is provided with a radial recess 40 which extends beyond the outer periphery of the shaft. Accordingly, if the key is sheared during rotation of shaft I8 the lubricating oil from chamber 39 will be released through passage 40 for adequately lubricating the engaging surfaces of the shaft and rotor member I9.

Key 20 has a drive fit in slot 4I in shaft I8 and the end edges of the key conform substantially to the contours of the ends of said slot. However, the fit at the ends is such that a very small amount of oil may iiow by centrifugal action between the end surfaces of the slot and key. This small amount of oil serves to prevent the accumulation of rust or the like between shaft I8 and rotor member I9 and the continuous lubrication of these surfaces insures initial free movement of the shaft if conditions necessitate the shearing of key 20. It also makes it easy to disassemble the rotor and shaft after substantial periods of operation without the necessity of applying destructive forces to the parts.

It may be noted that the holes for bolts 8 are symmetrically arranged with respect to a vertical plane through the axis of shaft I8 in Fig. 2 and that the other parts are so constructed that member 6 and cylinder I2 may be turned end for end if it is desired to operate the rotor in a direction opposite to that indicated by the arrow in Fig. 2. This makes it possible to use the same pumps in all installations irrespective of the direction of rotation required.

There is thus provided a rotary type pump which may be readily assembled and disassembled for inspection, cleaning and repair, said pump embodying novel means for continuously lubrieating the inner walls of the pump. Novel means are also comprehended for insuring free rotation of a positively driven rotating shaft or member in the event an element which is normally driven thereby is prevented for any reason from rotating. Additionally, the novel structure contemplated is adapted to prevent the accumulation of rust or the like between connected rotating parts.

Although only a single embodiment of the invention is illustrated and described in the accompanying drawings and the foregoing specication, it is to be expressly understood that the various features of the invention may be adaptable to other types of structures embodying rotatable parts. Various changes may also be made in the design and arrangement of parts illustrated without departing from the spirit and scope of the invention, as will now be apparent to those skilled in the art. For a definition or the limits of the invention, reference is had primarily to the ap- 'pended claims.

what is claimed is: I. In apparatus of the class described, a driven rotatable shaft having a closed chamber therein and an opening extending from `said chamber to rotate. in said casing and having a cylindrical bore,

therein, a rotatable member extending into said bore, said member having a closed chamber therein, and a key carried by said member and extending into a keyway in said element for drivably connecting said element and member, said key having a recess therein communicating with said chamber and terminating in the key within said keyway.

3. In apparatus comprising a casing, the comb ination of a rst rotatable member in said casing, a second rotatable member having a closed chamber therein, and means for drivably connecting .said members including a key of shearable material such as phenolic material carried by said second member and extending into a keyway in said first member, said key having a recess therein. the open end of which communicates with said chamber and the closed end terminates at a point radially outward from the periphery of said second member.

4. In apparatus comprising a rotatable element having a the combination therewith of arotatable member having a cylindrical portion thereof extending into said bore, said portion having a closed chamber therein and a slot in the peripheral wall thereof, said slot having end walls which converge toward the axis of said member and a key extending from said slot into said keyway, said key being shaped to have a drive fit between the side walls of said slotiand to have substantial engagement with said converging end walls, said key having a. recess therein communicating with said chamber and terminating in said key outside the periphery of said member.

5. In apparatus of the class described, a rotatable shaft having a closed chamber therein containing a supply of liquid lubricant and an opening connecting said chamber with the exterior of said shaft, and a rotor keyed to said shaft by a frangible key fitted in said opening, said key being provided with a recess communicating with said chamber and extending beyond the periphery of said shaft to release said lubricant when said key breaks.

GILTNER J. KNUDSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS cylindrical bore with a keyway therein,

Lignan Dec. 31, 1940 

